import java.util.Arrays;

public class Test {
    public static void main(String[] args) {
        String s1 = "12";
        String s2 = "23";
        String s3 = s1+s2;
        System.out.println(s3);
    }
    public static void main1323(String[] args) {
        StringBuilder stringBuilder = new StringBuilder();

    }
    public static void func(String S,char[] arr) {
        S = "hh";
        arr[0] = 'b';
    }
    public static void main111(String[] args) {
        String s = new String("asd");
        s = "bb";
        char[] a = {'a','b'};
        func(s,a);

        System.out.println(s);
        System.out.println(a);
    }
    public static void mai22n(String[] args) {
        String s = "ab!cdf@1 2@11";
      /*  String[] arr = s.split("@|!| ");
        for (String ss:arr) {
            System.out.println(ss);
        }
        String ret = s.substring(4,5);
        System.out.println(ret);
*/
        String ret = s.trim();
        System.out.println(ret);
    }
    public static void main222(String[] args) {
     /*   String s = "abc";
        char[] arr = s.toCharArray();
        for (char c:arr) {
            System.out.print(c+" ");
        }*/

        char[] s = {'a','b','c'};

        String ret =new String(s);
        System.out.println(ret);
    }
    public static void main11(String[] args) {
       /* String s = String.format("%d-%d-%d",2020,1,1);
        System.out.println(s);*/

        String str = "abcabd";
        String str1 = str.replaceAll("a","b");
        System.out.println(str1);

        String str2 = str.replace("a","c");
        System.out.println(str2);

        String str3 = str.replaceFirst("a","b");
        System.out.println(str3);
    }
    public static void main44(String[] args) {
        String s1 = "Hello";
        String s2 = "HELLO";
        System.out.println(s1.compareToIgnoreCase(s2));

        System.out.println(s1.toUpperCase());
        System.out.println(s2.toLowerCase());
        String SS = "hello";
        char[] sss = SS.toCharArray();
        for (char c:sss) {
            System.out.println(c);
        }
        char[] ss1 = {'a','b','c'};
        String ss2 = new String(ss1);
        System.out.println(ss2);
        String ss3 = ss1.toString();
        System.out.println(ss1);
        System.out.println(ss1);
    }



    public static void main333(String[] args) {
        String s1 = String.valueOf(123);
        String s2 = String.valueOf(12.44);
      /*  System.out.println(s2+1.1);
        System.out.println(s1+1);*/
        int ss1 = Integer.parseInt("123");
        System.out.println(ss1+1);
        double ss2 = Double.parseDouble("1.25");
        System.out.println(ss2+1);


    }
    public static void main33(String[] args) {
        Test test = new Test();
      //  System.out.println(test);
        String s = new String("sss");
      //  System.out.println(s);
        String str = "abcabbbbddddsfgga";
       // char s1 = str.charAt(2);
        int index = str.indexOf("ab",3);
        int index2 = str.lastIndexOf("ab",10);
        System.out.println(index2);


    }
    public static void main2(String[] args) {
        String s1 = "healo2";
        String s2 = "hello1";
        //System.out.println(s1.equals(s2));
        System.out.println(s1.compareTo(s2));


    }
    public static void main1(String[] args) {
        String s1 = "hello";
       // System.out.println(s1);
        String s2 = "world";
        //System.out.println(s1+" "+s2);

        String s3 = new String("hh");
        String s4 = new String("hh");
        String s5 = "hh";
        String s6 = "hh";

        //System.out.println(s3 == s4);
      //  System.out.println(s5 == s6);

        char[] ss = {'h','e','l','l','o'};
        String sss = new String(ss);
        System.out.println(sss.length());
        System.out.println("gg".length());

        String str = "";
        System.out.println(str.isEmpty());
        System str1 = null;
       // System.out.println(str1.isEmpty());

    }
}
